Stephen Webb at FT has been making battle with the resurgence of classical theism. Now he employs the help of Barth. His latest entry is a short treatment of Barth’s account of divine simplicity in Church Dogmatics II.1, §31. The appropriate section is “The Unity and Omnipresence of God,” pp. 440-490. It just so happens that I read this section today, in preparation for a Barth reading group tomorrow. So, it is rather fresh on my mind.
First, it should be clarified that Barth does not reject “simplicity” and “infinity” altogether. He is rejecting “absolute simplicity” and “absolute infinity,” which are derived from apophatic reflections upon creaturely limits. The “absolute” as such is not God’s absolute but, instead, something imposed upon God and limiting God. Barth is not denying God’s infinity, but he is expanding it to include spatiality and finitude — in accordance with Scripture. I will try to explain briefly.
As Barth has been doing this whole time in CD II.1, he is treating the divine perfections (attributes) as determinations of God’s love and freedom. God is the one who loves in freedom and is free in his love, as Barth defines God. The perfections of his freedom, such as unity and simplicity, are such that God determines their meaning; he is not determined by them. The reversal is what Barth perceives to have happened in the received tradition (orthodoxy), such as illustrated in Augustine, Anselm, and the Protestant scholastics. Statements of God’s simplicity are “put at the head,” not “in their proper turn,” as if God’s simplicity were derived from “the general idea of an ens vere unum” (446-447).
If God determines the meaning of his unity and simplicity, then these concepts are “not at our disposal” (448). They cannot be defined apart from “God’s self-demonstration” in his Word and work (459). Per usual, Barth gives a run through of passages from both the OT and the NT (see especially 451ff.). Following upon his exegesis, Barth will define God’s simplicity according to the determinations of his love:
…the simplicity of God consists in the trustworthiness, truthfulness, and fidelity which He is Himself…If He were divisible, dissoluble, or flexible, He would not be trustworthy…This divine simplicity, however, is not to be looked for in any other place than that in which the prophets and apostles found it, when it offered itself for them to find and they were found by it. [458-459]
So, God is without division in his unique self-determination as wholly faithful, not because God is bound by some prior concept of simplicity or infinity. Such prior concepts are answers to the question, what is necessary for existence to be extended beyond creaturely limitations? But, “The Christian doctrine of God has to face and answer questions put to it by the God who confronts man and not by the man who confronts God” (464). That should be memorized by every student of Barth. The concern to have a God who is without our limitations is actually a form of idolatry, and man will defend this “God” with the utmost zealotry. Rather, God determines his own “limits,” as his being derives from himself. He’s God. And God is without division in that he is wholly trustworthy and faithful. His fidelity is not one part of his essence, but of all. Nothing alongside him or apart from him can threaten his constancy and fidelity.
Barth gives an extensive treatment of the common coupling of “omnipresence” with “eternity,” as they are placed under the heading of “infinity.” Barth is convinced that “infinity,” as a predetermined concept, is doing more work than it should. It constrains God in his capacity to include finitude within his infinity. “God’s ‘infinity,’ if we want to use this expression, is true infinity because it does not involve any contradiction that it is finitude as well” (467). The point, for Barth, is that a concept of infinity that cannot contain (or make space for) the finite is not God’s infinity. As we have said, it would be a limitation provided by the concept, not by God’s own determination. As such, it would not be God’s infinity at all. Here is a longer excerpt:
We certainly do not deny that God is this too, that He is infinite, i.e., that He is not bound to the limits of space and time nor to the forms of space and time generally as the determinations of His creation. But we must add at once that God is infinite in His own divine way, and not in the way in which this can be said of created spirit. …The infinity which as a concept stands in antithesis to infinitude, and therefore to this extent the isolated concept of infinity, is quite insufficient to describe what God is in relation to space and time. God’s ‘infinity,’ if we want to use this expression, is true infinity because it does not involve any contradiction that it is finitude as well. For there is no reason why God in His essence should not be finite in the same perfect way as He is infinite. But to be finite in this perfect way necessarily means in such a way that His finitude does not prevent His being infinite, and therefore that while finitude is that which limits and is a determination of His creation, it does not involve any limitation or defect in God. 
So, Barth is “stretching” the concept of infinity to include, for God, the concept of finitude. This is not the first time that concepts have been stretched for theological reasons. It seems like ousia was stretched for the sake of God in the fourth century. For people who believe in the Trinity — wherein Greek categories are modified beyond all recognition — I find some of the criticisms of Barth a bit odd. The orthodox christology, likewise, has the temerity to say that one hypostasis can have two different natures in each’s fullness! I am beginning to think that Christianity has a habit of borrowing and significantly modifying the capacity of categories.